I'll post the instructions of that blog post here to provide more details about the technical set up required to create a WordPress multi site network

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Setting up the domains:

Setup your main domain. This may involve the basics like registering it, setting up the nameservers, setting up the hosting etc. Once you have the hosting setup and you are ready to upload the files, follow these steps before installing Wordpress.

Let's refer to your primary domain as www.primarydomain.com and let us refer to your secondary domain as www.secondarydomain.com.

Wildcard DNS: Create a subdomain on your primarydomain.com called "*" (without quotes). This will make sure that <some-random-sub-domain>.primarydomain.com does not return a 404 error.

Install Wordpress 3 at www.primarydomain.com as instructed in the official documentation and setup your first site.

Add the following line to your wp-config.php file define('WP_ALLOW_MULTISITE', true);

In the wordpress admin section go to Tools > Network. Choose subdomains amongst sub-domains and sub-directories. Follow the instructions on the screen to finish the network setup.

Once you finish the network setup you'll have the Super Admin menu activated on the admin screen.

Go to Super Admin > Sites. Add a new site (for the secondary domain). For now we'll have to set it up as a subdomain and we'll later map it to the main domain. Let's create it as secondary.primarydomain.com.

I'm a little confused with this part [code=auto:0]3.Wildcard DNS: Create a subdomain on your primarydomain.com called "*" (without quotes). This will make sure that <some-random-sub-domain>.primarydomain.com does not return a 404 error.[/quote]

But what about an exisiting sub domain WWW ?

Why would you not want a 404 for sub domains that don't exist?

If you use domain parking, it is either going to cause problems with duplicate content OR if it redirects to perform webforwarding you need to know what type of redirect is being performed 301 or 302 otherwise you won't get the desired link juice.

Some people set up wildcard sub-domains to capture typo traffic and try to track it. Other people set it up to just capture as may eyeballs as possible.

What would Google think of it? I've never seen a site penalized for using wildcards but it has been a long time since I've seen a site try to use them. I would guess that if you serve any content on the wildcards that it would probably be treated as duplicate content and filtered out.

If you anticipate drawing a lot of links to the site, using the wildcards might help you get some broken links fixed, or at least identify where to implement 301-redirects. But it might just be a waste of your time and resources (if defining a server record is much of a resource to waste).

I'm a little confused with this part [code=auto:0]3.Wildcard DNS: Create a subdomain on your primarydomain.com called "*" (without quotes). This will make sure that <some-random-sub-domain>.primarydomain.com does not return a 404 error.

But what about an exisiting sub domain WWW ?

Why would you not want a 404 for sub domains that don't exist?

If you use domain parking, it is either going to cause problems with duplicate content OR if it redirects to perform webforwarding you need to know what type of redirect is being performed 301 or 302 otherwise you won't get the desired link juice.

Hi Guys,

I've used live htttp headers to see what happened when you pull up a page or the root domain.

I noticed at the end of page rendering that a reference was made to the primary domain, but it looks like that has to do with setting a cookie or identifying what site is being requested.

When you request a page or the main root domain, a HTTP/1.1 200 OK status is given for the right URL, so it looks like everything is in order.

The wild card dns has to do with the ability to have multiple sites hosted on their own domain name, all the sites will make use of only one WP installation which makes updating a whole lot easier.

The domain mapping plugin uses the wild card set up to make that happen somehow, I'm not that technicall to give you a more clearer explanation...sorry.

Let us know how you get on, as having one WP admin account to control multiple customer domains given them their own CMS login is something I am considering getting into, so would really appreciate your feedback.